1. Field of the Invention
The present invention relates to relates to interbody and/or cement restrictor devices for implantation between a pair of adjacent vertebrae in order to provide support to the vertebrae and/or promote bone fusion between the vertebrae or for implantation within the intermediary canals of a femur, tibia or humerus.
2. Background Information
The disc between vertebrae of a human spine is sometimes damaged due to disease or injury, or may simply deteriorate due to age, disease, injury or congenital defect. With others, the vertebrae may become compressed or otherwise damaged. In these and other cases the vertebrae can become too closely spaced anteriorly which causes an undesired abnormal curvature of the spine with respect to lordosis or kyphosis.
Because of this, surgery may be utilized to place one or more spacers or interbody devices between adjacent vertebrae to provide proper spacing of the vertebrae and which may also promote fusion between the vertebrae. When a device of this type is utilized for the purpose of promoting fusion, it is often termed a fusion cage or an intervertebral fusion device. When so utilized, bone or bone fusion material is often placed about or in the interbody device(s) in order to promote growth of the bone between the adjacent vertebrae.
Interbody devices known as cement restrictors may also be used in bones such as the femur, tibia or humerus for the same or similar reasons as vertebral interbody devices. In these cases, the interbody device is implanted within the intermediary canal of the particular bone.
When interbody devices are used, it is desirable for them to engage as much surface of the bone as possible to provide support to the bone and to thereby reduce the likelihood of subsidence of the device into the bone resulting from contact pressure of the interbody device against bone surfaces. Subsidence can occur since part of the bone is somewhat spongy in nature, especially near the centers of the adjacent vertebrae.
In summation, the structure of interbody devices mainly functions to support the two adjacent vertebral surfaces, unless the interbody device is also used as a fusion cage within or around which to pack bone fusion material, or to act as a cement restrictor within a long bone. Because it is also desirable in such structures to maintain weight and volume as low as possible in order to make the device more compatible with the body, it is also desirable to make the interbody device as small and lightweight as possible, while still maintaining strength.
Accordingly, there presently exists a need for improved interbody devices.